How to find the domain name given an IP address

Overview

Domain names and IP addresses are relayed through the Domain Name System (DNS). The domain name connected to an IP address is given via a DNS pointer record, or PTR.

Reverse DNS lookups make use of DNS PTR records. A DNS lookup happens when a user types in a domain name to access it in their browser, comparing the domain name to the IP address. In contrast, a reverse DNS lookup is a request that starts with an IP address and gets a domain name.

The domain name for the given IP address can be fetched using the gethostbyaddr() function of the socket module in python.

The gethostbyaddr() function

The gethostbyaddr() function is used to retrieve the domain name for the given IP address.

Note: Refer to Socket programming in Python to learn more about socket module in python.

Syntax

socket.gethostbyaddr(ip_address)

Parameter

  • ip_address: This is the IP address for which the domain name has to be retrieved.

Return value

The method returns a tuple, (hostname, aliaslist and ipaddrlist).

  • hostname: This is the domain name.
  • aliaslist: This is a list of alternative host names for the same address.
  • ipaddrlist: This is a list of IPv4/v6 addresses for the same interface on the same host.

Example

import socket
def domain_name(ip_addr):
  dom_name = socket.gethostbyaddr(ip_addr)
  print("The domain name for " + ip_addr + " is", dom_name)
ip_addr = "8.8.8.8"
domain_name(ip_addr)

Explanation

  • Line 1: We import the socket module.
  • Lines 3–5: We define a function called domain_name that takes in an IP address and uses the gethostbyaddr() function to find the domain name function.
  • Line 7: We define an IP address, such as ip_addr.
  • Line 8: We invoke the domain_name function is with ip_addr as an argument.

Free Resources

License: Creative Commons-Attribution-ShareAlike 4.0 (CC-BY-SA 4.0)